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