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)(13,14,19,18)(15,20,25,28)(16,21,27,24)(17,23,26,22)(5,7)(6,9)(8,12)(10,11)(13,15)(14,20)(16,26)(17,27)(18,28)(19,25)(21,22)(23,24) involution — undirected(1,2,3,4)(13,16,18,24,19,27,14,21)(15,23,20,26,25,22,28,17)(6,10)(9,11)(13,14,19,18)(15,20,25,28)(16,21,27,24)(17,23,26,22)(7,12)(9,11)(13,17,18,23,19,26,14,22)(15,24,20,27,25,21,28,16)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.