[chipaca]

From the looks of it that's been generated by `circo`, which is part of GraphViz and describes itself as a “filter for circular layout of graphs” and

       circo  draws graphs using a circular layout (see Six and Tollis, GD '99
       and ALENEX '99, and Kaufmann and Wiese, GD '02.)  The  tool  identifies
       biconnected  components  and draws the nodes of the component on a cir‐
       cle. The block‐cutpoint tree is then laid out using a recursive  radial
       algorithm.  Edge  crossings within a circle are minimized by placing as
       many edges on the circle's perimeter as possible.   In  particular,  if
       the  component is outerplanar, the component will have a planar layout.
       If a node belongs to multiple non‐trivial biconnected  components,  the
       layout puts the node in one of them. By default, this is the first non‐
       trivial component found in the search from the root component.

[mmsc]

Doing a bit more digging, it's using cytoscape[0] which is similar to graphviz. If you search your favorite search engine with "Cytoscape Session Viewer", you'll find many websites displaying the same type of graphs (select layout: circle).

FYI, circo doesn't always output a circle. I recently created https://github.com/MegaManSec/SSH-Snake/blob/main/tools/SSH-... using circo.

[0] https://cytoscape.org/