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