"Winter landscapes by 1st grade - one day project" by Mrs. Knight's Smartest Artists. One day lessons can make great sub lessons. This one makes such a gorgeous work of art. Paint isn't a great medium for subs, but can be substituted with crayons or markers. If you will let your sub use markers, make sure you leave lots of instruction about how the students should use them.
"A Cup of Fantasy," at Arteascuola. These painted cups are so colorful. I am sure they can be recreated in crayon or marker. You could make step-by-step visuals pretty easily for this one.
"Patterns for the New Year," by Strong Rock Elementary Art Gallery blog. This teacher gives an overview of this lesson about goals for the new year. You could provide your sub with simple visuals and directions to go along with this lesson.
"Chinese New Year - Year of the Dog," by Centers and Early Finishers. This is a complete lesson with visuals and script at TeachersPayTeachers.
Here is another complete lesson about Chinese New Year.