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