I don't think that laptop has MXM graphics card so you cannot swap it out.
You have two option:
1. vidock if you have expresscard slot or 2. you can open the computer and use the mini pcie connector, connect mini pcie connector to pcie x16 converter and a desktop psu for power. But I don't think you want to do number 2 because you have no mobility at all. Either way, your graphics card will be very bottlenecked by the bandwidth and they cost money which IMO is not worth it and is better spend on a desktop gaming build or a gaming laptop if you need mobile gaming.
so if it has an express car slot, whats the next step??
Google for a product called ViDock which is an external casing for a desktop video card. There are a few versions range from about $200 - $300. The more expensive the case, the more powerful video card you can install. Of course you should find out what is the most powerful card you can install for each version before making your decision.
Don't forget, it's $200 - $300 + the price of the video card. Don't forget that you'll need to plug that baby into an A/C outlet.