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