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