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