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