Race and color weren't referred to in the constitution until the 15th amendment, which granted equal protection. You can argue parts talk about slavery in the abstract but could refer to any non-free person (prisoners for example).
Racism was institutionalized in many, many other ways but to say the constitution specifically is quite racist isn't really correct, it's more than race was left out.
Now the confederate constitution, that's an example of won't shut up about race.
Then after that the segregation, lynching, shootings, fetishization, housing bans, zoning laws...
Really racist every step of the way.