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