Go to Projects > Workflows.
At the top of your workflow, click on the task name.
Click "Add/Edit Subtasks"
Add your subtasks
Set your task color
Click save
How to set up custom workflow sub-tasks
Go to Projects > Workflows.
At the top of your workflow, click on the task name.
Click "Add/Edit Subtasks"
Add your subtasks
Set your task color
Click save