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