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