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