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