['Pretty' is not an adjective he's sure he would ascribe to it, nor expect. Though he won't correct her; it's a compliment in its own way, even if it's just another component in his design. Something required to designate him as an android within human society.]

It does. Blue, yellow, and red.

[A finger to indicate at his own temple, before dropping his hand back down into his lap.]

Blue is a default state. The higher the strain or the more taxing the mental processing -- whether due to internal or external factors -- the more likely the color will change. Extreme stress will lead to a red LED, though I obviously hope to avoid that as much as possible.