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