This is really cool and just up my alley since I'm always drawing state machines. However, I'd love to find a tool for drawing these state machine diagrams either with a UI or just a yaml file that's processed with a command-line tool.
If you're just looking for a tool that you can use to define (and play with) a state machine, take a look at https://sketch.systems - it's not a 'drawing' tool but you could export an XState object and put that in another tool
Depending on what you're trying to accomplish, you can use Graphviz (http://www.graphviz.org/) which accepts DOT input to produce graphs.
You may also be interested in a GUI-based DFA/NFA/PDA simulator I built, available here: http://automatonsimulator.com/. The target audience is CS students and was built based on notation found in Michael Sipser's "Introduction to the Theory of Computation." It allows you to: graphically define state machines, test against input strings, step-by-step debug, and export/import using a text format.
Thanks for the suggestions. I've used Graphviz before and found it super useful for automated graph generation for sure.
The tool you built also looks like it's close to what I'm looking for. I guess what I'm really looking for is a super slick and simple graph generator app, sort of like what https://mindnode.com/ is for mind maps/outlines. If I had more time, it's something I would like to build.
Does anyone have suggestions for these things?