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