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