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