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