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