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