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