I instruct sonnet-3.7-thinking in Cursor Agent mode to draw latex tikz diagrams for me and that works iteratively quite well.
Draw a circle, add a label to the circle, draw a box right to it, draw an arrow from the circle to the box, and so on.
I'm guessing for a lot of people draw.io and Excalidraw are probably the go-to. If you use draw.io (or something else), what do you like about it, or what do you wish was better?
[1] - https://app.vexlio.com/ for the curious
Draw a circle, add a label to the circle, draw a box right to it, draw an arrow from the circle to the box, and so on.