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