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