Depending on what trading job you are interviewing for? If its for a specific product then obv learn about that, i.e. if you want to be a derivatives trader then read Hull, but I would suggest to you reading something specific/complicated is not necessary. The worst question I got asked was what books have you read.. i hadnt read any but i still got the offer.
In a grad trading interview you are more likely to get asked about the core competencies, current market situation and problem solving questions.
Read the FT, everyday for 1 week before the interview (that is assuming you dont already) just to get you up to speed with the major stories right now. Develop a view (this is always important to show). Know what you want to do and why.
One thing we like when interviewing people is someone who knows or thinks something different.. know the subprime and the credit crisis but that isnt going to make you stand out from the crowd. Perhaps if asked the question about the current conditions say 'of course there is the crisis bla bla.. but i am sure you have been hearing about that all day.. so heres a story i found interesting...' this will show u didnt just learn the top headline for the interview but you actually know something (even if you dont) also if they want to know about the subprime/credit they will ask you after.
If you dont like this approach talk about the news but offer an opinion.. stick your neck on the line... it is a quality a trader needs and again will make you stand out.
Majorly importnat learn your competencies, HR love competencies and as a graduate HR have a big say, in fact in most banks HR will interview you a few times before they let you lose on interviews with business representatives.
So thats a lot of crap I have written, In summary:
Read the FT and learn your competencies. At this stage your social skills will get you a lot further than your knowledge.
Let us know how it goes.