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