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