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