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