Halloween Foaming Soap

I am always looking for new ideas to get my 5 year old to wash her hands.  We already use foaming soap, which gets quite expensive, so I poked around online and learned that you can make your own!  I have been doing this for about a year now, but still have to fight with my daughter to wash her hands.  I was walking by the bathroom the other day, when it hit me...why not make the soap fun colors?  With Halloween coming up, I thought orange would be a great color to start with.  This was made with 5 drops of yellow and 1 drop of red food coloring.  My daughter noticed it right away and this week she has been using the soap without my prompting her!  I may try scenting it next

What do you think?  What fun colors would you use?