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