To make a the superflip pattern on the 7x7 you follow the following series of moves:
1) Move the inner FIVE Layers clockwise (up) and the top layer (U) anticlockwise. Do both these steps 4 times.
2) Then rotate the whole cube along the X-axis clockwise and along the Y-axis clockwise.
Repeat the above two steps 3 times.
3) Move the inner THREE Layers UP and the top TWO layers anticlockwise. Do both these steps 4 times.
4) Then rotate the whole cube along the X-axis clockwise and along the Y-axis clockwise.
Repeat the above two steps 3 times.
5) Move the inner ONE Layers UP and the top THREE layers anticlockwise. Do both these steps 4 times.
6) Then rotate the whole cube along the X-axis clockwise and along the Y-axis clockwise.
Repeat the above two steps 3 times.