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