The South Pole of the Earth doesn't point to a specific constellation. It points towards a specific spot in the sky, which is currently occupied by the constellation Octans.

However, due to the precession of the Earth's axis, the position of the South Celestial Pole (the point in the sky the Earth's South Pole points to) gradually changes over time. In about 7000 years, the South Celestial Pole will be in the constellation Grus.

So while Octans is the current constellation the South Pole points to, it won't always be the case.