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