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