Green would be worn on her feast day as it occurs during Ordinary Time.
White or blue vestments may be worn on this Feast Day. The color blue is permitted only on Feast Days dedicated to the Blessed Virgin as it was her favorite color.
The priest would wear white vestments on the feast day of Saint Catherine of Siena, which is celebrated on April 29th. White is the liturgical color used to honor saints and feasts of special importance in the Catholic Church.
The Triduum, Holy Days of Obligation, and Feast Days of Martyrs
Roman Catholic AnswerTo the best of my knowledge, none of the doctors of the Church died as martyrs, so their feast days would be white. If they did die as martyrs, the priest would be wearing red.
White or blue and white since it is a feast of the Blessed Virgin.
The color of vestments for the feast of the Immaculate Conception is white.
In the Catholic Church, red is worn for the feast days of martyrs (signifying blood), including the Apostles (except John), and also on days focused on Jesus' death on the cross (e.g. Palm Sunday and Good Friday), and when the focus is the Holy Spirit (Pentecost Sunday, confirmation masses) signifying the fire of the Holy Spirit. See the Wikipedia page on "Liturgical_colours" for a more complete answer, including the variations for other churches.
White. New Year's Day is also the celebration of the Solemnity of Mary and it is all still part of the Christmas Season--and the color of the Christmas Seeason is White. The secondary color that can be used is Gold. Christmas Season runs from "sundown"/4pm Christmas Eve/Dec 24 through the Feast of the Baptism of Our Lord--which is usually the third Sunday after Christmas.
White
Roman Catholic AnswerThe priest wears red on Pentecost as it is a Feast of the Holy Spirit. It has been referred to as Whitsuntide as it was the last day that the new Christians wore their white robes: Whitsuntide=White Sunday.
Red is the color of the day on feast days of martyrs.
Feast beast least priest released east