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