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