Graphene is such a new and rapidly expanding field that to my knowledge there aren't really any textbooks on it, and it would be pointless because anything printed is likely to be out of date in a few years. You would be better served reading the current papers in the field. If you don't have the requisite knowledge to understand them, then it's essential you study that first in any case.
Personally, I have skipped the books and read a lot of patents. Identify your area of interest (transparent conductive films, for example. or thermally conductive polymers) and start grabbing patents using google patent search. Save as .pdf. At the end of each patent, examples give detailed step by step instructions. In general, these are easier to read than scientific publications. Best of all, free.