Interview process in EY is relatively simple, and from feedback gathered from many different colleagues, varies significantly depending on who the interviewer is.
There is no one standard set of questions to be asked or areas to be tested. There is also no tests to be completed, including aptitude ones (not for mine anyway).
Rather there are three stages to the interview process.
Stage 1: HR Interview
The HR interview is mainly a formality, filtering out those who cannot present themselves or speak in a fluent and clear manner. It can be done in person or over the phone. It has taken from several hours to several weeks for HR to revert, so its hard to say when you will get that callback. In addition to that, potential candidates resumes are often lost - so make sure you do check on your status often, and more importantly, get names of the people you are talking to.
Stage 2: Senior Manager / Director interview
This stage is the key and probably the only real stage of interview. The Senior Manager or Director will probe you with questions, ranging from typical or non-relevant questions. Typical questions involved why EY, how do you see yourself fitting in, describe yourself in a working environment, strengths and weaknesses, what do you know about what we do, etc. For a fresh graduate, the interviewer wants to see the aptitude to learn and develop skills rather than expecting actual technical skills.
Take this stage to ask questions of your own as this person would be most suited to answer your questions truthfully.
Stage 3: Partner Interview
A full formality stage where the partner ask simple and straightforward questions, often touching on the same questions the previous interviewer has answered. This stage matters little other than just your first contact with the partner.