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