Once a table object is created there are many ways to format the cells to give the information some visual uniqueness.  Highlight a cell by left-clicking and then right-click to show the pop-up list.  Choose Cell Borders to open the Cell Border Properties dialogue box.  You may now change the line weight or color of the cell border. You can also manipulate the border visibility in the right portion of the dialogue box.

An addition to last week's tip of using your symbol blocks in the cells would be to turn off the border around the cells with the blocks.