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