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