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