I found the following prayer in the current issue of the Knights of Columbus' Guild Newsletter:
We thank you, God our Father, for those who have responded to your call to priestly ministry. Accept this prayer we offer on their behalf: Fill your priests with the sure knowledge of your love. Open their hearts to the power and consolation of the Holy Spirit. Lead them to new depths of union with your Son. Increase in them profound faith in the Sacraments they celebrate as they nourish, strengthen and heal us.
Lord Jesus Christ, grant that these, your priests, may inspire us to strive for holiness by the power of their example, as men of prayer who ponder your word and follow your will.
O Mary, Mother of Christ and our mother, guard with your maternal care these chosen ones, so dear to the Heart of your Son. Intercede for our priests that, offering the Sacrifice of your Son, they may be conformed more each day to the image of your Son, our Lord and Savior, Jesus Christ.
Saint John Vianney, universal patron of priests, pray for us and our priests.