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