Hi Bethany,
While there isn't an option to move the legend to a different location, the legend panel is collapsible so a reader can open and close it as needed when looking at the map. If you wanted to move the legend and are or have access to a developer you could download the source code for the app from GitHub and make that customization.
Looking at your screenshot, however, I'd suggest that detailed legend isn't needed in your story map. Readers won't be able to tell the difference between the shades of color nor will they be able to easily match a color from the map to a value in your legend. Many people in your audience may not even have a sense for what a value of 25.67 vs. 29.45 means on the CalEnviroScreen 3.0, and I think what you really want them to understand where the good vs. bad results were found or where a specific set of conditions exist.
You can more simply and effectively communicate what the colors in your map mean by coloring key words in your text like High , Medium, and Low or Good and Bad. Another technique is to use a screenshot of a color ramp in the side panel.
Check out this story map as an example: http://arcg.is/1ODu4Na There are a lot of maps, but none of them use the dynamic legend widget.
If it's important for readers to know the results at a specific spot on the map you can instruct them to click the map to see a pop-up that will show that value.
There are more details and other ideas and tips about how to orient readers to your map in this story map: http://arcg.is/2cmQzG4
I hope this is helpful!
Owen
Owen Evans
Lead Product Engineer | StoryMaps