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