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