If you mean by max and min that you have 7 spaces or divisions for positive and 7 for negative on both axes, then you can place the origin at the centre of the paper and label it 0 for both axes; then mark 1 to 7 and -1 to -7 on both axes. Join the point (7,7) to point (-7,-7) which passes through the origin. The y values represents g(x). The straight line is y=g(x)=x, the graph of the function g.