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