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