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