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