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