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