Differences in power-law indices (α_λ) between the V and i bands (x-axis) and the B and V bands (y-axis) shown in colored crosses: red for early-red, blue for early-blue, and gold for early-yellow events. The three black open symbols represent the error-bar-weighted means for each population. (KSN-2018ku and KSN-2021V are included in the early-red population as green crosses; see the text). The power-law rise of the events in the four labeled quadrants separated by horizontal and vertical dashed lines evolve in B − V and V − i as follows: (I) blueward in both colors; (II) blueward in B − V and redward in V − i; (III) redward in both colors; and (IV) redward in B − V and blueward in V − i.