In the late sixties and early seventies if you called a black man “colored” he would respond, “Who are colored people?” By then they wanted to be called black.
In 1961 the official word was Negro.
However, if some clerk who was filling out the birth certificate asked Obama’s mother where the father was from and she replied “Africa”, it’s possible this is what was written down.
Seems more likely that she would have replied Kenyan, and the clerk would have written that down as an indication that the father was a foreign national