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)(13,14,19,21,18,24,16,22)(15,17,25,28,26,20,23,27)(6,9)(7,11)(13,15)(14,20)(16,23)(17,24)(18,26)(19,25)(21,27)(22,28) involution — undirected(1,2,3,4)(13,16,18,19)(14,21,24,22)(15,25,26,23)(17,27,20,28)(5,7,8,11)(6,10,9,12)(13,16,18,19)(14,22,24,21)(15,25,26,23)(17,28,20,27)(6,9)(10,12)(13,17,19,28,18,20,16,27)(14,23,21,15,24,25,22,26)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.