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