Most sewing machines come with a simple plastic cover which may suit you just fine but why not use you sewing machine to make a great cover for it?
My sewing machine actually didn't come with a cover so I decided to make one.
First pick your fabric and measure how much you will need (this depends on your own sewing machine, as they are all different sizes). Mine is 70x40cm.
I used this quilting fabric filler as a backer for the fabric and it worked great.
Cut it to size, then sew your fabric at each side on top of the quilted fabric.
Drape the fabric over your machine to find out where the handle slot needs to go. Run a pencil line on top of it and then cut a slot for it. Then sew back the edges for a nice finish.
Decide whether or not you want to have a pocket on the outside first - I thought this was great as I had no where to put my cables.
Make sure you cut the fabric big enough so you can wrap it around the bottom of the fabric and stitch it at the edges. Make sure you hem the top edge nicely first.
Once it's all complete, then add some ribbon at each end so that you can tie it together.