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