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