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