It would depend on the liturgical season for a memorial or optional memorial. During Ordinary Time it would be green or, if the saint was a martyr, red; if is a feast or solemnity then non-martyrs would be white. During Lent or Advent the color would be violet for memorials.
Saint Sebastian was a martyr, the patron Saint of the Catholic War Veterans. The liturgical color of the Vestments worn on that day is red.
White vestments are worn
White, or white and gold, is the color of vestments during the Christmas Season.
The priest wears red vestments on Palm Sunday.
violet, because it's lent
He wears red vestments when presiding over Good Friday services.
Red vestments are worn on Passion (Palm) Sunday.
Either blue or red depending on what story you are talking about
Roman Catholic AnswerWhite is the color for the Solemnity of Christ the King. Gold or Silver may be substituted.
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.
Often, a banner matching priest vestment color is in front of altar, the color being associated with the church time, like purple as it is in Lent. It does not always match; if priest is doing funeral he will wear white but the altar may still be purple.
You can wear red anytime you like. The priest wears red vestments on Pentecost and the feasts of martyrs.
Saint Patrick's Day falls during Lent so the vestment color would be violet.