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