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