Selfhosted

Sure. What that guy is using is actually not the most-interesting diagram style, IMHO, for automatic layout of network maps, if you want large-scale stuff, which is where the automatic layout gets more interesting. I have some scripts floating around somewhere that will generate very large network maps

run a bunch of traceroutes, geolocate IPs, dump the results into an sqlite database, and then generate an automatically laid-out Internet network map. I don't want to go to the trouble of anonymizing the addresses and locations right now, but if you have a graphviz graph and want to try playing with it, I used:

goes looking

Ugh, it's Python 2, a decade-and-a-half old, and never got ported to Python 3. Lemme gin up an example for the non-hierarchical graphviz stuff:

graph.dot:

graph foo {
    a--b
    a--d
    b--c
    d--e
    c--e
    e--f
    b--d
}

Processed with:

$ sfdp -Goverlap=prism -Gsep=+5 -Gesep=+4 -Gremincross -Gpack -Gsplines=true -Tpdf -o graph.pdf graph.dot

Generates something like this:

That'll take a ton of graphviz edges and nicely lay them out while trying to avoid crossing edges and stuff, in a non-hierarchical map. Get more complicated maps that it can't use direct lines on, it'll use splines to curve lines around nodes. You can create massive network maps like this. Note that I was last looking at graphviz's automated layout stuff about 15 years ago, so it's possible that they have better layout algorithms now, but this can deal with enormous numbers of nodes and will do reasonable things with them.

I just grabbed his example because it was the first graphviz network map example that came up on a Web search.