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