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