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