From the Encyclopedia of Cats

Terrific                             

cats tail is standing up tall.

Back off

when tail twitches back and forth.

Angry

when tail is bushy

Ready for fun and afection 

ears strait up

I’m listening

eyes wide open and looking at you

Sleepy

eyes halfway open

Frightened

bug eyed

I love you

blinking and winking at you

Watch out

ears down ward

Realaxed/ill

eyes are clouded

Stay away

eyes stairing strait at you