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