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