If the color of food coloring is purple, what colors are reflected? What colors are absorbed?

Before answering this question, we need to know what kind of color is in purple food coloring. Is it a purple dye, or is it a mixture of colors like blue and red? Single pigments are normally “brighter,” or have greater color saturation, than mixed pigments. That is why, for example, if you go shopping for acrylic or oil artists’ paints, the tubes have the names of the pigments on them. The colors are not pure red, yellow, green, blue, and so on—the paint company supplies the single pigment so that the artist has maximum control (but also needs to know a great deal about the nature of individual pigments).
We might expect that a purple pigment would make a nice bright purple food colorant. I found a helpful page in the American Chemical Society’s Chem Matters series. It lists dyes approved for use in food. No purple dyes are included. Thus, we conclude that purple food coloring includes a mix of approved red and blue dyes.
The Chem Matters page (link included below) states that blue food coloring absorbs its complementary color of orange most strongly, while red absorbs its complement of green most strongly. It is important to recognize that a dye in a water solution absorbs a range of colors. You do not simply delete one pure hue and keep everything else. Thus, the red dye absorbs some blue along with the green (and some yellow), and the blue dye absorbs some red along with orange and yellow. This is why the result is less saturated than a purple pigment might be.
We would expect the mixed dye, then, to transmit or reflect some blue, violet, and some red, while absorbing most of the green-yellow-orange color range.
https://www.acs.org/content/acs/en/education/resources/highschool/chemmatters/past-issues/2015-2016/october-2015/food-colorings.html