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