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