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