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