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