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