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