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