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