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