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