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