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