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