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