The standard for any tidally locked body, of which Europa is a member, is to have the 0 longitude be the point at the center of the planet-facing side. That being the case, the middle of the map should be the portion facing Jupiter, the edges the part that never faces Jupiter. See Wikipedia for the referenced quote below:
Tidally-locked bodies have a natural reference longitude passing through the point nearest to their parent body: 0° the center of the primary-facing hemisphere, 90° the center of the leading hemisphere, 180° the center of the anti-primary hemisphere, and 270° the center of the trailing hemisphere.
That being said, the source image for your map is found at the USGS website. The far right side is 0 degrees longitude, the far left 360, of the image shown below:
The darker region, which is the central piece for your image, is centered around 250 degrees longitude. In fact, looking at the database of features on Europa, we find out that Dyfed Regio is 10 lat, 250 longitude.