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