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