I will pray for you when the sun rises and sets every day.(这种译法一定要注意三单加s和专属名词加the的问题!)
或：I will pray for you everyday at/on sunrise and sunset.
I will pray for you at/on sunrise and sunset everyday.
只是语序不同罢了,都正确!
个人比较欣赏二楼的翻译,很有诗意：
I would pray for you on/at every sunrise and sunset.