Wikipedia's Suggestions as of May 24, 2021

I'm not buying the Anaximander connect, because he wasn't bald:

The Internet also seems to have gained consensus about Pythagoras, but I can't believe that any painter would have chosen to depict Pythagoras without headwear.

I'd suggest caution again as to who knew what when as to those busts. I'll mention as the exemplar caveat that caricature of Epicurus in the Nuremberg Chronicle. If you don't have a reference, you can draw/paint someone any way you like. It would be nice if we had access to a full set of preparatory sketches of the School of Athens to see the planned and the final appearance of all these figures.