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