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