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