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