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)(11,12)(13,15)(14,16)(19,23)(22,24)(25,26,29,33)(27,31,35,30)(28,32,37,40)(34,39,36,38)(18,21)(22,24)(25,27,29,35)(26,30,33,31)(28,36,37,34)(32,39,40,38)(2,3)(6,7)(9,11,14,13)(10,15,16,12)(17,18)(19,22)(20,21)(23,24)(25,27)(26,31)(28,34)(29,35)(30,33)(32,39)(36,37)(38,40)(1,3,5,2)(4,7,8,6)(9,12,14,15)(10,11,16,13)(25,26)(27,30)(28,32)(29,33)(31,35)(34,38)(36,39)(37,40)(1,4,5,8)(2,6,3,7)(9,13,14,11)(10,15,16,12)(17,19,20,23)(18,22,21,24)(25,28)(26,32)(27,34)(29,37)(30,38)(31,39)(33,40)(35,36)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.