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)(11,14)(12,15)(13,18)(16,22)(17,19)(20,24)(21,23)(25,26)(27,35)(28,37)(29,34)(30,38)(31,33)(32,36)(39,40)(1,3)(2,6)(4,7)(5,8)(10,11)(12,19)(16,18)(20,21)(25,27,31,36)(26,32,33,35)(28,29,38,39)(30,34,37,40)(10,11)(15,17)(16,18)(23,24)(26,33)(27,36)(28,38)(34,40) involution — undirected(1,3,5,8)(2,6,4,7)(9,11,14,10)(12,15,19,17)(13,18,22,16)(20,23,21,24)(25,28)(26,30)(27,29)(31,38)(32,34)(33,37)(35,40)(36,39)(1,3)(2,7)(4,6)(5,8)(9,12)(10,15)(11,17)(13,21)(14,19)(16,24)(18,23)(20,22)(25,29)(26,34)(27,28)(30,32)(31,39)(33,40)(35,37)(36,38) involution — undirected(1,4,5,2)(3,7,8,6)(9,13)(10,16)(11,18)(12,20)(14,22)(15,23)(17,24)(19,21)(25,30)(26,28)(27,34)(29,32)(31,37)(33,38)(35,39)(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.