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