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