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