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