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