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