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