Complex sentence: In principle, EL lamps can be made in any color, however the most commonly used greenish color matches well with the peak sensitivity of human vision so it produces the greatest apparent light output for the least electrical power input.
Split into simpler sentences: In principle, EL lamps can be made in any color. However, the commonly-used greenish color closely matches the peak sensitivity of human vision, producing the greatest apparent light output for the least electrical power input.