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)(11,16)(12,14)(13,20)(15,19)(17,21)(18,22)(23,24)(28,36)(31,37)(34,40)(38,39) involution — undirected(1,3,5,4)(2,6,7,8)(9,11)(10,15)(12,16)(13,18)(14,19)(17,22)(20,23)(21,24)(25,26)(27,32)(28,37)(29,33)(30,35)(31,36)(34,38)(39,40)(9,10,14,12)(11,16,19,15)(13,17,21,20)(18,23,24,22)(25,27)(26,30)(28,34)(29,35)(31,38)(32,33)(36,40)(37,39)(1,2)(3,8)(4,6)(5,7)(9,12,14,10)(11,16,19,15)(13,20,21,17)(18,23,24,22)(25,28,29,36)(26,31,33,37)(27,34,35,40)(30,38,32,39)(1,2)(3,6)(4,8)(5,7)(9,11)(10,16)(12,15)(13,18)(14,19)(17,23)(20,22)(21,24)(25,27)(26,32)(28,34)(29,35)(30,33)(31,39)(36,40)(37,38) involution — undirected(1,4,5,3)(2,6,7,8)(9,13)(10,17)(11,18)(12,20)(14,21)(15,22)(16,23)(19,24)(25,26)(27,30)(28,31)(29,33)(32,35)(34,38)(36,37)(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.