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