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