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