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