I have wished for this sort of thing from time to time as well, however I think it would get too gnarly to be useful when routing gets complex, with side chaining and multiple outs. You end up with a lot of crossed “wires”. One of the advantages of being “in the box” is potentially really complicated routing. It might be better to show one channel at a time. Or one node at a time. For example, I start at an instrument analog input, see that it goes to 2 tracks (say lead and backup guitar), then go to the lead channel and see that it routes to an effects channel, a side chain, main out, and 2 cue outputs in control room. I choose any of these to see their routing, and so on. Unfortunately, the node-by-node approach doesn’t help much with drag and drop, bypassing and adding routes, and so on.
Something like this already exists in matrix form as part of the mixer window, but the workflow might be better in graph form. The dilemma is still between showing too much (thus confusing) versus not showing enough (thus diminished usefulness).