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