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