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