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