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