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