One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,8)(5,6)(9,10)(11,16)(12,23)(13,21)(14,29)(15,19)(17,28)(18,25)(20,34)(22,33)(24,32)(26,37)(27,38)(30,31)(35,36)(39,40) involution — undirected(2,6)(7,8)(9,11,15,22)(10,16,19,33)(12,24,27,39)(13,29,30,18)(14,31,25,21)(17,34,35,26)(20,36,37,28)(23,32,38,40)(1,3,5,4)(2,7,6,8)(9,12,25,36,15,27,14,28)(10,17,29,38,19,35,18,23)(11,20,31,39,22,37,21,24)(13,26,33,40,30,34,16,32)(1,4,5,3)(2,8,6,7)(9,13,14,16,15,30,25,33)(10,11,18,21,19,22,29,31)(12,26,28,32,27,34,36,40)(17,20,23,24,35,37,38,39)(2,6)(7,8)(12,27)(17,35)(20,37)(23,38)(24,39)(26,34)(28,36)(32,40) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.