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