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