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