Try wiping her mouth with a damp tissue after shes been fed and also hr eyes. With her eyes wipe upwards gently, not down, that spreads the stain further.
The staingin is not to do with colouring inthe food but the PH values of the saliva which can be affected by food. I found a bit of tomato ppuree mixed with a bit of water and then the food helps. Doesn't disappear overnight - but will go in time. My Orange boy had a terrible eye stain at one bit - he has none now after following the regime above.
hth
PS - it won't stop you showing her but of the stains under the eyes in particular are bad then it will go against her and it is avoidable - so get the tomatoe going