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