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