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