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