In a large mixing bowl, whip cream until it forms stiff peaks.
Fold in the sweetened condensed milk and vanilla.
Divide ice cream into three bowls. Add red food coloring to one, blue to another and leave the third white.
Alternate plopping bits of ice cream into a freezer safe container to make a nice swirl of colors. Tap the pan on the counter a few times to even it out and then freeze for 5-6 hours or overnight.
Allow to soften on the counter for 5-10 minutes before serving.