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)(13,14,18,22)(15,16,21,20)(17,23,26,27)(19,24,28,25)(5,7)(6,9)(8,12)(10,11)(13,15,18,21)(14,20,22,16)(17,28,26,19)(23,24,27,25)(1,2,3,4)(13,16,19,27,18,20,28,23)(14,21,24,17,22,15,25,26)(6,10)(9,11)(14,22)(16,20)(23,27)(24,25) involution — undirected(7,12)(9,11)(13,17,28,21,18,26,19,15)(14,23,25,20,22,27,24,16)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.