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