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