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