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