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