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