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