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)(13,14)(15,17)(16,24)(18,21)(19,25)(20,22)(23,26)(27,28) involution — undirected(1,2,4,3)(5,6)(7,10)(8,9)(11,12)(13,14)(15,17)(16,24)(18,21)(19,25)(20,22)(23,26)(27,28)(6,9)(10,11)(13,15,22,21,18,20,17,14)(16,23,28,27,26,24,25,19)(5,7,8,12)(6,10,9,11)(13,16,22,28,18,26,17,25)(14,19,15,23,21,27,20,24)(1,3,4,2)(13,17,18,22)(14,15,21,20)(16,25,26,28)(19,23,27,24)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.