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