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