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