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