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