  We analyze the rainbow tensor model and present the Virasoro constraints,
where the constraint operators obey the Witt algebra and null 3-algebra. We
generalize the method of W-representation in matrix model to the rainbow tensor
model, where the operators preserving and increasing the grading play a crucial
role. It is shown that the rainbow tensor model can be realized by acting on
elementary function with exponent of the operator increasing the grading. We
derive the compact expression of correlators and apply it to several models,
i.e., the red tensor model, Aristotelian tensor model and $r=4$ rainbow tensor
model. Furthermore, we discuss the case of the non-Gaussian red tensor model
and present a dual expression for partition function through differentiation.
