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