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