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