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