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