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)(11,19)(12,22)(13,17)(14,20)(15,16)(18,24)(21,23)(25,26,29,33)(27,34,37,31)(28,38,30,32)(35,40,36,39)(2,5)(6,7)(9,11,13,16)(10,15,17,19)(12,20,23,18)(14,22,24,21)(25,27,29,37)(26,31,33,34)(28,36,30,35)(32,39,38,40)(9,12,14,15,13,23,24,19)(10,16,18,22,17,11,20,21)(27,35)(28,30)(31,39)(32,38)(34,40)(36,37)(1,3,4,8)(2,6,5,7)(10,17)(12,23)(15,19)(18,20)(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.