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