Here’s some of stuff I eyeball in my line of work:

• https://en.m.wikipedia.org/wiki/Control-flow_graph
• https://en.m.wikipedia.org/wiki/Parse_tree -https://en.m.wikipedia.org/wiki/Automata_theory
• https://en.m.wikipedia.org/wiki/Hasse_diagram
• https://en.m.wikipedia.org/wiki/Binary_search_tree

And then source code itself can be beautiful.

If you are serious about this, we could work through some concepts.

Cheers!