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