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