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