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