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