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