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