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