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