You can set TCAD's property in inspector,ColorOfHot property can change hot's color,HotSize property can change hot's size,HotShow property it can hide or show hot when you select shape.

Also,you can do it by code.

Code example:

procedure TMainFrm.Button1Click(Sender: TObject); 
begin 
  MyCAD1.ColorOfHot:=clRed; 
  MyCAD1.HotSize:=8; 
  //MyCAD1.HotShow:=False; 
end;