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