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