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