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