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)(25,26,30,33)(27,35,36,39)(28,31,29,34)(32,37,40,38)(1,2)(3,5)(4,6)(7,8)(26,31)(28,29)(32,39)(33,34)(35,40)(37,38) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,11,13,19)(10,14,15,23)(12,21,22,18)(16,24,20,17)(25,27)(26,32)(28,38)(29,37)(30,36)(31,39)(33,40)(34,35)(2,6)(5,8)(10,15)(14,23)(16,20)(17,24)(26,33)(27,36)(31,34)(37,38) 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.