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