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