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