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