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