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