Many job applicants try to answer this question directly in one of the following ways or, to make it worse, answer it with a question:
- Blood runs through the vessels therefore my brain colour is red...
- I think it is red now because I have a huge headache...
- Why are you interested in my brain?
- Why are you asking this question?
- There is no colour in my brain...
- Cut it and you will see...
The above answers (also questions) would not give you a good ESL teaching position.
In fact, the reason why the question was asked by the recruiter was to find out what colour represents your personality best.
You can answer that your brain is red because you are always hot - you are always on fire with new ideas, therefore your brain is always full of new plans, etc.
There are more possible answers:
Your brain can also be transparent because you are an honest person.
And even more:
Your brain can be like a rainbow because you are full of interesting, colourful ideas.
See also a similar question here...
You will also find useful ESL job interview questions-answers here: