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