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