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