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