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