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