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