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