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