On my other web site there is a page that describes in detail how to prepare a basic Gantt Chart using a spreadsheet. The other day Tony Miller wrote and asked me if I could prepare a Gantt Chart in which the bars are different colours. So, your wish is my command: take a look at this video file and see how it’s done!
You will find other examples in Chapter 15 of my book, The Excel Project: Excel for Accountants, Business People … from the Beginning, that will help you to use the techniques you need to build this chart in your other work.
The link that follows takes you to a page in my ExcelMaster website. Gantt Charts with Coloured Bars.