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