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