The following keyboard controls can be implemented:

1. TAB/Left-right arrow keys to switch between the color choosing area and the drawing grid area.
2. Enter/Space/Return to select a color/fill a cell with the already selected color/erase if the erase icon is selected.
3. In color selector column, up/down arrow keys to navigate through colors in the color selector column.
4. In drawing grid area, arrow keys to navigate through the cells.