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