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