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