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