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