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