Food coloring??? No, really, there is no way to make a white grape juice a pink (rose) juice without the skins. See the quoted method I found on the web.
"Vatting or Pressing. At this step in the process, the rosé producer chooses between two vinification options: direct pressing, which yields a pale pink wine, or maceration/bleeding, which yields a darker-colored pink wine.
Direct Pressing. This technique, which is used by the majority of Provence producers, yields a rosé that's light in color, because the dark skins stay in contact with the clear juice for a very short period of time. In direct pressing, the grapes – either destemmed or in clusters – are immediately pressed in a wine press (pressoir) to release the juice. The pale pink juice is then delivered to the fermentation tank.
or
Maceration and bleeding. This is a steeping-and-draining process. During maceration, the crushed grapes soak in a tank for between two and 20 hours at a cool, tightly controlled temperature (usually ranging from 60° to 68°F). As the juice and skins comingle, the skins release their pigments and delicate aromas. The winemaker tests for color and, determining that the maceration period is complete, opens a filter in the bottom of the vat to drain – or bleed – the juice into the fermentation tank using the force of gravity. Exactly how long the vatting time should last is one of the questions that make rosé winemaking so delicate. It must be long enough for the red pigments to give the wine its pink color. But it mustn't be so long that the tannins in the skins begin to detract from the wine's lively elegance."