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