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