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