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