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