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