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