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