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