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)(11,19,21,24)(12,17)(13,18)(14,16)(15,20,23,22)(26,30)(27,33)(28,35)(31,38)(32,36)(37,39)(9,11)(10,15)(12,20)(13,22)(14,21)(16,23)(17,19)(18,24)(25,26,29,32)(27,31,33,39)(28,36,35,30)(34,38,40,37)(10,16)(15,23)(17,18)(19,24)(25,27,29,33)(26,31,32,39)(28,34,35,40)(30,37,36,38)(9,12,14,13)(10,17,16,18)(11,20,21,22)(15,19,23,24)(27,33)(31,39)(34,40)(37,38)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.