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