The Root sits at the base of the bodygraph and corresponds in position to the lowest of the classical seven chakras, which is also usually called the root.
A straightforward correspondence
Both schemes place a centre at the base of the series and both associate it with grounding, drive and the physical. Of the nine centres in the bodygraph this is among the least altered in the borrowing, which makes it a useful reference point when working out how far the other eight have moved.
The arithmetic
The classical scheme most often cited in modern Western usage has seven centres. The bodygraph has nine. The G or Identity centre and the Spleen have no classical counterpart at all. Of the remaining seven, the Head, Ajna, Throat, Sacral and Root correspond reasonably closely; the Heart and Solar Plexus positions carry assignments close to the reverse of the classical ones, which is set out in the articles on those two centres.
Both ends of the comparison
The sevenfold chakra scheme is one arrangement among several described in Indian tantric traditions, and the version in wide Western circulation is a popular settlement rather than a single original.
Human Design was published by Ra Uru Hu in 1987, and this atlas records it as a contemporary system rather than as ancient or inherited material.
Sources Rainbow Body: A History of the Western Chakra System from Blavatsky to BrennanKurt Leland with The Origins of Yoga and Tantra: Indic Religions to the Thirteenth CenturyGeoffrey Samuel, The Human Design SystemRa Uru Hu (Alan Robert Krakower)