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