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)(25,26,31,29)(27,33,38,40)(28,39,37,32)(30,34,36,35)(2,6)(7,8)(9,11)(10,14)(12,18)(13,17)(15,21)(16,20)(19,23)(22,24)(25,27,36,28,31,38,30,37)(26,32,34,40,29,39,35,33)(1,3,5,4)(2,7,6,8)(11,17)(14,20)(18,23)(21,24)(25,28,30,27,31,37,36,38)(26,33,35,39,29,40,34,32)(1,3,5,4)(2,7,6,8)(9,12)(10,15)(11,18)(13,19)(14,21)(16,22)(17,23)(20,24)(25,29,31,26)(27,32,38,39)(28,40,37,33)(30,34,36,35)(1,4,5,3)(2,8,6,7)(12,19)(15,22)(18,23)(21,24)(25,30,31,36)(26,34,29,35)(27,37,38,28)(32,40,39,33)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.