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