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