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)(11,18)(12,20)(13,17)(14,15)(16,21)(19,22)(23,24)(26,27)(31,33)(32,34)(38,39) involution — undirected(2,6)(3,7)(10,15)(11,17)(12,21)(22,24)(25,26,30,27)(28,33,36,31)(29,32,37,34)(35,39,40,38)(1,3,5,7)(2,4,6,8)(10,15)(13,18)(16,20)(22,24)(29,37)(32,34)(35,40)(38,39)(1,4)(2,7)(3,6)(5,8)(9,11,14,17)(10,13,15,18)(12,19,21,23)(16,22,20,24)(25,27,30,26)(28,33,36,31)(29,34,37,32)(35,39,40,38)(9,12)(10,16)(11,19)(13,22)(14,21)(15,20)(17,23)(18,24)(25,28,30,36)(26,31,27,33)(29,35,37,40)(32,38,34,39)(9,13)(10,17)(11,15)(12,22)(14,18)(16,23)(19,20)(21,24)(25,29,30,37)(26,32,27,34)(28,35,36,40)(31,38,33,39)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.