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