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