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