The root position Dominant 7 arranged Root, 5th, 7th, and 3rd (low to high) has three shapes that we can use. We can play them on the low four, middle four, and high four strings. Line up the lowest note, in this case the root note, to the pitch that you are looking for.
Dominant 7 (R,5,7,3) on the low four strings:
Dominant 7 (R,5,7,3) on the middle four strings:
Dominant 7 (R,5,7,3) on the high four strings:
The chord shapes are different because of the guitar tuning. Fourths between all strings except for one major third between the third and second strings.