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