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