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