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