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