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