Chile Colorado is not spicy but can be made spicy if you want it to be! Using both the ancho chile peppers and guajillo peppers will not make the stew spicy, it is the chiles de arbol that add the heat.  They are 15 to 30 times spicier than ancho chiles and 6 to 12 times spicier than guajillo chiles.  You can omit the chilies de arbol altogether or add 1-3 chilies de arbol; 1 being mild-medium and 3 being very spicy.  You can also skip the chiles de arbol and spice up your Chile Colorado recipe with cayenne pepper to taste.