The graph showing the number of eggs left based on the number made is a straight line decreasing from (0, 12) to (6, 0).

Step 1: Number of eggs left = 12 - 2x, where x is the number of omelettes made.
Step 2: Plot the points (0, 12), (1, 10), (2, 8), (3, 6), (4, 4), (5, 2), (6, 0) on a graph.
Step 3: Connect the points to form a straight line.

The graph would look like a straight line decreasing from the point (0, 12) to the point (6, 0). The line would be sloping downward from left to right.