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)(13,14,18,19)(15,20,25,22)(16,21,17,26)(23,24,27,28)(5,7,8,12)(6,9,10,11)(13,15,18,25)(14,20,19,22)(16,23,17,27)(21,24,26,28)(2,4)(14,19)(15,22)(20,25)(21,26)(23,28)(24,27) involution — undirected(6,10)(9,11)(13,16,18,17)(14,21,19,26)(15,23,25,27)(20,24,22,28)(7,12)(9,11)(13,17,18,16)(14,21,19,26)(15,24,25,28)(20,23,22,27)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.