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