Hi Tina. The BANA Math committee is making some suggestions regarding the application of the new Formats Guidelines to Nemeth transcriptions. Follow Formats guidelines for bulleted lists including using the symbol that the Guidelines show [braille]_4
Nemeth has its own rules for the presentation of typeform. Color is not included. In your example, it does not appear that color is necessary for the understanding of the expressions. Nemeth says not to indicate typeform if it has no meaning. If you decide that the color is necessary, you will need to devise a way to show that. Do not use the Formats symbols because they can too easily be confused with mathematical symbols (shapes).
I ordinarily leave out the color in situations like yours because it interferes with reading the math expressions, especially in the lower grades.