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