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