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