HH, Sir Godfrey Gregg D.Div

The colour of the ordinary minister cassock and clerical attire, in general, is black. For the regular minister, the cassock is totally black.

For cardinals, the buttons, trim, and inside hem are scarlet silk.
For patriarchs, archbishops, bishops, protonotaries apostolic and prelates of honour, the buttons, trim and inside hem are amaranth red.
For chaplains to the Patriarch, purple.

For liturgical and public ceremonies of the Church, cassocks are of one colour;
White for the Patriarchs
Scarlet for Cardinals
Purple for archbishops, bishops, protonotaries apostolic, and prelates of honour
Black for other ministers

In some dioceses, especially in the tropics, permission is granted for cassocks to be white and then trimmed in the colour designating the status of the cleric.

The symbolism of the cassock is as follows;

The Roman collar symbolizes obedience.
The Sash or cincture around that waist, chastity.
The colour black, poverty. Moreover, black is a colour of mourning arid death for the minister, the symbolism is dying to oneself to rise and serve the Lord as well as giving witness of the Kingdom yet to come.

Buttons on Single breasted

39 = Represents the 39 Articles of the Church of England and/ or the stripes of our Lord’s Scourging (40 -1). (My Choice)
33 = Represents Christ’s earthly years (Tends to worn by RC priests or those too short to wear 39 who’ll then get evenly placed)