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