I've seen one done in neutrals ranging from white all the way to gold/tan - I think some were tone on tone and some had little patterns to them. It was lovely because of the range of colors in the arches.
It's admirable that you want to make this pattern for your grandmother. I made one for one of my kids about 10 years ago made up in greens/blues/pink and white. For me it was a labor of love pattern/quilt. However, I've warned my other kids not to plan on this pattern for any of their future quilts! Of course now I'm better at quilting and who knows...