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