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