We present a graphical way of describing invariants and covariants in (four-dimensional) general relativity. This frees us from the complexity of treating many suffixes. Two new off-shell relations between (mass) invariants are obtained. These are important for 2-loop off-shell calculations in perturbative quantum gravity. We list all independent invariants with dimensions of (mass) and (mass). Furthermore, the six-dimensional Gauss--Bonnet identity is expressed in terms of the independent invariants.