Think the bolded part is worth remembering: as in, why is Diana wearing it, who is she around and where is she?
From the image she appears to be in space and not a mosque, so thats one thing. Regarding the list you provided... I think thats a rather strict version you've uncovered since quite alot of muslim women tend to wear quite colorful hijabs and in wealthy places like Dubai, they also tend to wear a fair amount of jewlery. What Diana might be getting wrong however is how loose she appears to keep it. Also it might bear noting that that hijab is only the headwear, not the entire outfit... and Diana's appears to be slipping off.
This is speculation
tend, might & appears - aren't facts, they are your interpretation
I agree, in the western world, you may see more colourful garb, compared to the oppressive full black outfit. However if (I say if as I don't know where the above image is from) Diana is on her way to the middle east, as an ambassador she should know the customs. However, it seems to me, with the fewest assumptions that the creative team were pushing their coexist claptrap, without paying attention to the sensitive matters that pertain to certain practices