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