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