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