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