Here are Cala and Iota from the VIPER-RSR artbook. But there is no colored version of the Julietta character design sheet in the VIPER-RSR artbook. I also checked my copy of the Colorful PureGirl magazine that had Cala on the cover, but it's absent there, too. All the artbooks produced after the RSR art book are black-and-white only, so unless we find another source (another promotional magazine perhaps?) or the owner of the original cel (Edage Katsura probably) puts it on the market, we may never see a colored version for Julietta. You could always color it yourself of course but that doesn't count.
