Just as "orange" in English originally meant an orange tree, "だいだい" in Japanese originally meant another kind of citrus tree here in Japan. Both of them now also mean the almost same color of the different fruits that those trees bear as you may already know. ／I am sorry that I don't know much about fruits, but I heard that "だいだい" is called "sour orange" or "bitter orange".

Ohh I see, that makes sense. Thank you so much @Nora Kuma! ありがとございます！

オレンジ is the notation of the color. You can make sure of the pronunciation at the following URL. https://ja.forvo.com/word/%E3%82%AA%E3%83%AC%E3%83%B3%E3%82%B8/#ja 「だいだい」is Japanese traditional name of the color, "Orange (オレンジ）". It means the same. オレンジ is more common than だいだい.