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