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