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