N.H. Rev. Stat. Ann. § 656:25

The state primary election ballots of all parties shall be printed upon colored paper or on plain white paper with a printed, colored header, but no ballots of any political party shall be printed upon paper or printed with a printed, colored header, of the same or a closely similar color as the ballots of another political party. On the back of each ballot to be used in hand-count polling places shall be printed in prominent type the name of the party.