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