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