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)(13,14,16,20,17,19,25,24)(15,18,23,26,22,21,27,28)(2,4)(5,7,8,6,10,12,9,11)(13,15,16,23,17,22,25,27)(14,18,20,26,19,21,24,28)(6,7)(8,9)(11,12)(13,14)(15,21)(16,24)(17,19)(18,22)(20,25)(23,26)(27,28) involution — undirected(2,4)(6,11)(7,12)(14,19)(15,22)(20,24)(23,27) 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.