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