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