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