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