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