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