Split Color On Rows In Table

I am creating a table with two rows(one of which is the header), and 8 column headings. In the 2nd row, i am trying to apply 3 different colours that span various length across the row. I want the row to loop adding one colour directly to the end of another, but adding this to the correct length of colspan for each colour.

The code below is what i have done so far, but i only get a blue colour in the 3rds cell.
Eventually i would like to have a variable length of row, as i do not yet know how many rows i need (this will be dependant on something else). But i would like the colour method to be applied to each row.

Also i need to be able to make colspan variable so after each loop, it will be updated by the new column amount ....