This is a black version of Dogmeat's armor, but the straps and hardware are their original colors. It works for all versions of his armor. This will also override his helmet too, so it will be black. I just haven't found the item/the base id to be able to show it in a screenshot yet.

1. Place the texture folder into C:\Program Files (x86)\Steam\steamapps\common\Fallout 4\Data. If you already have the texture folder, place the contents inside into the folder.

2. Open the Fallout4.ini file in your Documents folder: (...Documents\My Games\Fallout4) and find the line: sResourceDataDirsFinal
Replace it with: sResourceDataDirsFinal=STRINGS\, TEXTURES\ and save the file!