Coffee is usually consumed in the morning. While you cannot force your peep to make coffee, many people have reported that if they turn on the game early in the morning (usually before 10 am), they can usually catch a peep making coffee at that time.

morning in the game, especially if they're tired or exhausted. Maybe they'll even make a grand latte.

Pause your game once they're exhausted in the evening and then unpause it in the morning and they will likely go make coffee. Keep "throwing them" at the coffee maker or counter until they do. You can also try reversing day and night under Options on the main menu so that it's morning instead of evening in the game when you play in the evening.