In a large bowl, cream the shortening and powdered sugar until smooth. While mixer is on low, mix in the egg, vanilla and baking soda. Gradually mix in 2 cups of flour with the mixer. Gradually mix in a little more of remaining flour until you have a soft "play-doh type dough. If dough is crumbly, gently knead the dough with your hands. If it is too sticky , mix in a little more flour.
Divide dough into three equal parts into glass bowls. To color, add a couple of drops of red food coloring and work into dough with your hands until desired color of pink. Do the same for the yellow color. To the third section of dough, mix in the cocoa powder until really well blended.
On a flat and floured surface, roll each color into a log shape, about 12 inches long. Place two of the colors side by side on a large sheet of plastic wrap. Place the third color on top, resting, on the other two. Using your hands, try to form the dough into a triangle shape. Use flour ob your hands when needed, so it doesn't stick to your hands. Cover tightly with plastic and pat firmly, so colors fuse together and stick. Chill for 25 minutes. Preheat oven to 350 degrees F.
When ready, unwrap and slice about 24 (1/2 inch) pieces. Place onto a baking sheet lined with parchment paper. Bake in preheated oven for 12 to 14 minutes or until edges are lightly golden.
Sprinkle with cinnamon/sugar(optional) as soon as they come out of the oven or leave as is. Cool completely, store in airtight container.