FYI, here is a hand-edited version of the above with modified bounding box & all nodes filled with white (i.e. not transparent). Also note that the cluster labels are now outside the cluster.
digraph {
graph [bb="0,0,246,997"];
node [label="\N" style=filled fillcolor=white]; // added fill
{
ext1a [height=0.5,
pos="179,904",
width=0.83048];
ext1b [height=0.5,
pos="101,904",
width=0.84854];
}
subgraph clusterext1 {
graph [//bb="60,518,238,953",
bb="60,540,238,910", // hand edited to adjust bb
fillcolor=lightblue,
label="obj XYZ",
labeljust=l,
lheight=0.21,
lp="92.5,941.5",
lwidth=0.68,
style=filled
];
{
graph [rank=same,
top=true
];
ext1a;
ext1b;
}
{
graph [bottom=true,
rank=same
];
ext1c [height=0.5,
pos="123,544",
width=0.83048];
}
subgraph clusterint1 {
graph [bb="68,590,230,858",
fillcolor=lightpink,
label="",
style=filled
];
node [shape=rect];
{
int1c [height=0.5,
pos="195,688",
width=0.75];
int1d [height=0.5,
pos="123,688",
width=0.75];
}
int1a [height=0.5,
pos="113,832",
width=0.75];
int1b [height=0.5,
pos="123,760",
width=0.75];
int1a -> int1b [pos="e,120.56,778.1 115.47,813.7 116.53,806.32 117.78,797.52 118.96,789.25"];
int1e [height=0.5,
pos="123,616",
width=0.75];
int1a -> int1e [pos="e,107.39,634.23 101.95,813.61 96.263,803.62 89.919,790.58 87,778 76.149,731.24 72.892,715.88 87,670 89.882,660.63 95.048,651.42 \
100.58,643.39"];
int1b -> int1c [pos="e,177.16,706.35 140.8,741.7 149.28,733.45 159.59,723.43 168.93,714.35"];
int1b -> int1d [pos="e,123,706.1 123,741.7 123,734.41 123,725.73 123,717.54"];
int1c -> int1e [pos="e,140.84,634.35 177.2,669.7 168.72,661.45 158.41,651.43 149.07,642.35"];
int1d -> int1e [pos="e,123,634.1 123,669.7 123,662.41 123,653.73 123,645.54"];
}
ext1a -> int1a [pos="e,129.15,850.13 164.68,887.81 156.59,879.23 146.26,868.27 136.97,858.42"];
ext1b -> int1a [pos="e,110.07,850.1 103.97,885.7 105.23,878.32 106.74,869.52 108.16,861.25"];
int1c -> ext1c [pos="e,136.97,559.94 190.43,669.8 184.72,649.83 173.86,616.26 159,590 154.8,582.58 149.4,575.11 144.08,568.45"];
int1e -> ext1c [pos="e,123,562.1 123,597.7 123,590.41 123,581.73 123,573.54"];
}
subgraph clusterext2 {
graph [//bb="8,219,238,510",
bb="8,251,238,472" // hand edited
fillcolor=lightblue,
label="obj wow",
labeljust=l,
lheight=0.21,
lp="40,498.5",
lwidth=0.67,
style=filled
];
{
graph [rank=same,
top=true
];
ext2a [height=0.5,
pos="123,461",
width=0.83048];
}
{
graph [bottom=true,
rank=same
];
ext2b [height=0.5,
pos="123,245",
width=0.84854];
}
{
int2b [height=0.5,
pos="51,317",
shape=rect,
width=0.75];
int2c [height=0.5,
pos="123,317",
shape=rect,
width=0.75];
int2d [height=0.5,
pos="195,317",
shape=rect,
width=0.75];
}
subgraph clusterint2 {
graph [bb="16,291,230,415",
fillcolor=lightpink,
label="",
style=filled
];
node [shape=rect];
int2a [height=0.5,
pos="123,389",
width=0.75];
int2b;
int2a -> int2b [pos="e,68.843,335.35 105.2,370.7 96.721,362.45 86.412,352.43 77.07,343.35"];
int2c;
int2a -> int2c [pos="e,123,335.1 123,370.7 123,363.41 123,354.73 123,346.54"];
int2d;
int2a -> int2d [pos="e,177.16,335.35 140.8,370.7 149.28,362.45 159.59,352.43 168.93,343.35"];
}
ext2a -> int2a [pos="e,123,407.1 123,442.7 123,435.41 123,426.73 123,418.54"];
int2b -> ext2b [pos="e,107.84,260.74 68.798,298.7 78.167,289.59 89.77,278.31 99.833,268.52"];
int2c -> ext2b [pos="e,123,263.1 123,298.7 123,291.41 123,282.73 123,274.54"];
int2d -> ext2b [pos="e,138.16,260.74 177.2,298.7 167.83,289.59 156.23,278.31 146.17,268.52"];
}
subgraph clusterext3 {
graph [// bb="84,64,162,211",
bb="84,94,162,171",
fillcolor=lightblue,
label="And More",
labeljust=l,
lheight=0.21,
lp="121,199.5",
lwidth=0.81,
style=filled
];
{
graph [rank=same];
ext3a [height=0.5,
pos="123,162",
width=0.83048];
}
{
graph [rank=same];
ext3b [height=0.5,
pos="123,90",
width=0.84854];
}
ext3a -> ext3b [pos="e,123,108.1 123,143.7 123,136.41 123,127.73 123,119.54"];
}
ext1c -> ext2a [pos="e,123,479.43 123,525.82 123,515.69 123,502.6 123,490.92"];
ext2b -> ext3a [pos="e,123,180.43 123,226.82 123,216.69 123,203.6 123,191.92"];
"The End" [height=0.5,
pos="123,18",
width=1.1374];
ext3b -> "The End" [pos="e,123,36.104 123,71.697 123,64.407 123,55.726 123,47.536"];
start [height=0.5,
pos="140,979",
width=0.75];
start -> ext1a [pos="e,170.1,921.66 148.66,961.8 153.39,952.95 159.36,941.75 164.76,931.65"];
start -> ext1b [pos="e,109.9,921.66 131.34,961.8 126.61,952.95 120.64,941.75 115.24,931.65"];
}
Giving: