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