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