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