Ah, thank you for saying this. I'm in the middle of drafting a fairly complicated visualization for something I'm working on. I avoided red-green contrasts because that's the most common form of colourblindness, but I thought red-purple-blue would be distinguishable. I'll have to try out green-yellow-blue instead.

Obviously that won't work for all kinds of colour blindness either but I can't figure out a straightforward way of representing this particular thing without colour ... it's literally about a graph colouring problem. Patterns/textures maybe? But then the nodes would have to be larger than I'd like so that there's enough surface area in each node to recognize the pattern, and then it would become very crowded.