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