gc (https://graphviz.org/pdf/gc.1.pdf) says
402 3249 automata (go_parser.gv)
So, approximately 3249 edges, or 16 edges per node. That makes for a messy (edge-filled) graph.
And indeed trying all the engines (dot, fdp, neato, twopi, and circo) with these args added to the command line -Gnslimit=2 -Gnslimit1=2 -Gmaxiter=5000 - though not with optimal attribute values - gave pretty useless graphs. (Circo never finished)
Here are some more hints - Dot command seems to never end - #6 by steveroush