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