I think the document definately needs some colour to give it some life and make it stand out a little more. Its boring looking through a black and white document, but it cant be something that is over powering as the work within the PDF is the most important and that varies from spread to spread.
To get and idea of what colours to use I looked through the yearbook to see what colours are present within the artwork that is displayed.
It is evident that throughout the yearbook there is a particular focus on Blue's, Green's and Red's. These are the most prominent colours and the ones which are used the most throughout the student work. As I don't want to introduce a colour that will totally go against the work and clash with what is being shown, it makes sense to use a colour which is within the artwork, so it all compliments each other and to eye it all blend nicely together.
Selected colours to try within the yearbook as a highlight colour.
Using the three colours within the PDF document to test which will work best.
The red is too dominant within the document and may take over the layouts and distract from the content itself. This leaves the blue and green.
They are both within the same colour hue and both have a pastel feel to them. Looking back through the yearbook, I think there is more green present within the artwork, so I think using the green is a better option and one which will compliment the content of the yearbook, but still be a strong colour to use on spreads that don't have the variation of colour from the artwork.
The document shots below show how the green is integrated into the spreads throughout the yearbook. It is used as a highlight colour and brings some life into the design, uplifting it to make it more interesting to look at.