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