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