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