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