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