If you want a jailbreak tweak that allows you to edit the colors of the 3D Touch menus, 3DColorChanger is your choice because it allows you to do this and best of all, it is free.
After installing this tweak on the device, you can start configuring your selection of colors from the app settings -> 3DColorChanger.
The preferences panel is fortunately very easy to understand, with no more than a color picker that gives you the ability to make multiple combinations.
You can adjust the hue, lightness or darkness of the color, and you can even set your own alpha (transparency) level to touch more or less pronounced 3D menus when opened.
Then we'll show the alpha level setting of a particular color, just as an example. It's amazing what you can do with so few settings: