The pink color is because the plant gets sun stressed. If you’ve tried putting it out in full sun and if it still hasn’t helped then I would recommend using an LED light in the 5000K range (daylight), 1500-2000 lumens and upto 30 watts should help. LED/ Grow lights are what people in the plant world use to sun stress their plants consistently and it gives better results than putting it out as the sun is not harsh all day long. LED lights with these specifications should work for houseplants and you need not buy expensive grow lights. Make sure the plant gets used to the bright light slowly as direct exposure can cause sun burn. Good luck