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 https://sketch.systems - it'

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 https://sketch.systems - it's not a 'drawing' tool but you could export an XState object and put that in another tool