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