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