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