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