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