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