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)(11,13)(12,15)(14,16)(19,23)(21,24)(26,30)(27,33)(28,36)(38,40)(9,11)(10,15)(12,14)(13,16)(17,18,20,22)(19,21,23,24)(26,30)(28,36)(31,34)(35,39)(11,12)(13,15)(17,18)(19,21)(20,22)(23,24)(25,26,29,30)(27,34,33,31)(28,32,36,37)(35,40,39,38)(1,2)(3,5)(4,6)(7,8)(9,12,14,11)(10,15,16,13)(25,27,29,33)(26,31,30,34)(28,35,36,39)(32,38,37,40)(1,3,4,7)(2,5,6,8)(9,13,14,15)(10,11,16,12)(17,19,20,23)(18,21,22,24)(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.