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