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