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