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