At this point only solid colours are possible. Typically it is best practice to use solid colours in order to keep the visualization clean and easy to read. Would you mind sharing why you'd like a stripy colour so I can share your use case with our products team?
Hello Sarah - though it is not possible to provide a "stripy color" for a particular dimensional value, you can however provide a custom color if you wanted a value to stand out - by using the color by expression option in the properties panel.
(providing this information for those that come across this type of question and wondering how to color by formula / expression)
For example - you can us the following with HTML color names