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