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