Hi Sivaji,
Sorry for another "you probably need to upgrade" response to your question, but if you look through the Knowledge Base on Scatter Plot (https://support.seeq.com/space/KB/153518135/XY%20Plot), you'll see that a lot of these capabilities have been added. For example, starting in version 46, you can color by fixed date ranges, allowing more coloring options by time as you mention.
The workaround on your version I believe would be to make each year its own condition using Custom Condition or something like that (one condition would be only the year of 2019, another condition being 2020 for instance). In this case, when you color by condition, it would be a different color for each condition.