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