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