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