The graphics.pas file has a ColorToString() function that will convert a valid TColor value to it's string representation using a predefined constant (if possible) or a hexadecimal string. The StringToColor() function provides the reciprocal function, taking a predefined color constant string or hexadecimal string and returning the TColor value. Example:

procedure TForm .Button Click(Sender: TObject);
begin
  Memo .Lines.Add(ColorToString(clRed));
  Memo .Lines.Add(IntToStr(StringToColor('clRed')));
end;