I was looking at [this] (http://www.omniglot.com/language/colours/multilingual.htm) I understand the connection to colonialism in a lot of them, but what I don't understand is why it was adopted, but other native words were kept for other colors.
It's because purple's not a fruit.
The currently cultivated orange is the product of several citrus varieties that originate in Eastern Asia and India. The earliest cognate we have for "orange" is the Snaskrit नारङ्ग (nāraṅga). It appears as far back as 500 BC in the Sushruta Samhita, a text which among other medical topics, describes medicinal uses for plants. As the fruit moved westward, so did this name for it. We see the word in Persian, then Arabic, and eventually Turkic, Germanic, and Romance languages. And with most of these cognates, the word is shared between the color and the fruit: Spanish naranja and anaranjado, Arabic برت قال and برتقالي .