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