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)(27,32)(33,38)(34,39) involution — undirected(1,2,5,4)(3,6,7,8)(9,11)(10,15)(12,21)(13,16)(14,19)(17,22)(18,23)(20,24)(25,26,30,31)(27,28,32,36)(29,33,37,38)(34,35,39,40)(2,4)(6,8)(10,16)(13,15)(17,20)(22,24)(29,37)(33,38)(34,39)(35,40) involution — undirected(3,7)(6,8)(9,12,14,23)(10,17,16,20)(11,18,19,21)(13,22,15,24)(25,27)(26,28)(29,34)(30,32)(31,36)(33,35)(37,39)(38,40)(1,3)(2,6)(4,8)(5,7)(9,11)(10,15)(12,21)(13,16)(14,19)(17,22)(18,23)(20,24)(25,28)(26,32)(27,31)(29,35)(30,36)(33,39)(34,38)(37,40) involution — undirected(1,4,5,2)(3,8,7,6)(9,13,14,15)(10,11,16,19)(12,22,23,24)(17,18,20,21)(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.