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