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