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