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)(11,15)(12,20)(13,17)(14,19)(16,21)(18,22)(23,24)(25,26,29,32)(27,33,35,30)(28,31,36,38)(34,39,40,37)(2,6)(4,7)(9,11)(10,14)(12,18)(13,19)(15,17)(16,22)(20,23)(21,24)(28,36)(31,38)(34,40)(37,39) involution — undirected(1,2)(3,4)(5,6)(7,8)(9,10,13,17)(11,14,19,15)(12,20,21,16)(18,23,24,22)(25,27,29,35)(26,30,32,33)(28,34,36,40)(31,37,38,39)(1,3)(2,4)(5,8)(6,7)(9,10)(11,14)(12,16)(13,17)(15,19)(18,22)(20,21)(23,24) involution — undirected(1,4)(2,3)(5,7)(6,8)(9,11)(10,15)(12,18)(13,19)(14,17)(16,23)(20,22)(21,24)(25,28,29,36)(26,31,32,38)(27,34,35,40)(30,37,33,39)(1,3)(2,4)(5,8)(6,7)(9,12,13,21)(10,16,17,20)(11,18,19,24)(14,22,15,23)(25,26)(27,30)(28,31)(29,32)(33,35)(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.