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