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