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