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