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