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