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