Certified GKH Gardening Expert
There tends to be two main colors- Light pink, and dark pink. Some pinks are so light that they look white. This is subject to change throughout time with growing conditions and care. Generally, more color means it is healthy, and well cared for.
If you start noticing a pronounced, dark pink, then you may be seeing cross pollination with another species nearby, leaving the new seeds with some color once they flower.
here is an article that will help you to care for the grass: https://www.gardeningknowhow.com/ornamental/foliage/pampas-grass/growing-pampas-grass.htm