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