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