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