Color data consists of 3 values. So if you want to store them in one cell, you will have to store them as a string of text. For example "255,0,255" (but without the quotation marks). And then separate them into 3 numbers for rbg() expression:
Set colorVar to Array.at(0,2)
Sprite set color to rgb(int(tokenat(colorVar,0,",")), int(tokenat(colorVar,1,",")), int(tokenat(colorVar,2,",")))
.
Another option is to pre-calculate all color values. For example, rgb(255,0,255) returns number 16711935. So you can store it in the array and use directly in "Set color" action, without the rgb expression.