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