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