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