What is the ruling on reading the Qur’an from a Mus'haf with colored letters, or from a Mus'haf in which the لفظ الجلالة (the majestic word "Allah") is in red?

There is no harm in reading from a mus'haf (copy of the Quran) with colored letters. The Salaf (pious predecessors) used to color some letters of the mus'haf to distinguish the Companions' orthography from the Tabi'in's (successors') vocalization, and to differentiate between hamzat al-qat' ( قطع ) and hamzat al-wasl ( وصل ), and so on.

The student Abdullah mentioned in his book: "Al-Muhtawi al-Jami' li-Rasm al-Sahaba wa Dabt al-Tabi'in" that every omitted letter in the Companions' orthography is written in red, every hamzat al-qat' is written in yellow, the starting dot for hamzat al-wasl is written in green, and the dot follows its letter, so it is written in the color of its letter.