One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(3,8)(6,7)(9,10,14,16)(11,19,22,38)(12,23,27,37)(13,28,25,18)(15,30,31,20)(17,34,33,26)(21,39,29,35)(24,36,40,32)(1,2)(3,7)(4,6)(5,8) involution — undirected(2,6)(5,7)(9,11,14,22)(10,15,16,31)(12,24,27,40)(13,29,25,21)(17,35,33,39)(18,36,28,32)(19,37,38,23)(20,34,30,26)(2,7)(3,8)(5,6)(10,16)(15,31)(17,33)(18,28)(19,38)(23,37)(32,36)(35,39) 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.