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