Answer:  

Mrs. Lucille Davies, who is teaching how to make soap at a secondary school, kindly answered the question above.
 
 
The soap without colouring is an off white...kind of light beige. We use a few drops of food colouring in the final step.
 
A recipe for making soap is in the textbook Nelson Chemistry 12, published by Nelson Thomson in 2001 or so, Ontario (Canada) edition... I co-authored it. 
 
As I understand it, soap was originally noticed when people saw bubbles form when rain fell on ashes where they would cook meat outdoors...sort of like an outdoor campfire pit. The bubbles/lather were found to be very effective in washing grease away, much better than water alone. In fact, soap had been formed when the animal fat was heated with the ashes which contain a strong base. 
 
We can make soap now by heating NaOH with any type of animal fat or vegetable oil...lard, shortening, corn oil etc. The fat can be dissolved first in a little ethanol. The mixture must be heated gently until the reaction is complete...the mixture turns from a liquid to a pudding-like consistency. At that point, the soap molecules are formed...the fat molecules break down into fatty acids and glycerol...and the sodium attaches to the fatty acids. 
 
These soap molecules now have a 'dual personality'...the sodium ion end mixes well with water, and the hydrocarbon end of the fatty acid mixes well with grease...so when you run water over the soap and grease, the soap molecule pulls the grease off with it in the flowing water. Voila, clean hands.
 
A few other steps are needed to finish the soap preparation...add some calcium chloride solution to precipitate the soap, rinse with a  weak acid such as vinegar to neutralize any unreacted NaOH, and add scent or colouring...shape the soft soap and let dry.
 
It's lots of fun, and the process links well in an organic chemistry unit on carboxylic acids, or even in any acid/base unit in general chemistry.
 
The mass production of soap had a major impact on hygiene and health. Before that, people used to live in rather unclean conditions...and smelled pretty bad! :-)

I hope this is helpful.
 
 
Acknowledgement
We would like to thank Mrs. Lucille Davies for her kind answer.  Please e-mail to Mrs. Lucille Davies (daviesl@limestone.on.ca), if you have any questions related to this article.