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)(15,17,23,22)(16,19,26,27)(21,25,28,24)(5,7)(6,9)(8,12)(10,11)(13,15)(14,17)(16,24)(18,23)(19,21)(20,22)(25,26)(27,28) involution — undirected(1,2,3,4)(13,16,20,27,18,26,14,19)(15,21,17,25,23,28,22,24)(6,10)(9,11)(13,14,18,20)(15,17,23,22)(16,19,26,27)(21,25,28,24)(7,12)(9,11)(13,17,20,23,18,22,14,15)(16,25,27,28,26,24,19,21)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.