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