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