maxillaria rufescens with yellowing leaves

[Shadeflower]

The yellowing is too much light. You can tell because only the top leaves closest to the light have been affected.

Watering it more won't harm as maxilaria's like to drink a fair bit but these can also easily suffer from root rot so I wouldn't overdo it as the problem is the light not so much the watering.

Ps: It looks more like a cattleya than a maxillaria though...