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