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