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