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