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