To change the styling of our generated diagrams with PlantUML we can use the skinparam command. We can set for example font size, style, color, background colors and much more. We can change the style for a specific element or for the whole diagram. We can even set specific styling options for stereotypes. The settings for the stereotype are then applied to all elements in our diagram with that stereotype. We must append <<stereotype name>> to the skin parameter name.

In the following example PlantUML description we apply custom background colors to each stereotype:


/' Set custom background colors for the default
   component elements and the specific stereotypes. '/
skinparam component {
    BackgroundColor #ff6666
    BackgroundColor<<Database>> #ccff66
    BackgroundColor<<Spring service>> #66ccff
    BackgroundColor<<Spring REST controllers>> #66ffcc
    BackgroundColor<<Spring repository>> #66ffff
    BackgroundColor<<Mail server>> #ffcc66

actor User
[Third party application] as ThirdPartyApp

together {
    [PostgreSQL database] as PostgresDB <<Database>>
    [Mail server] as Mail <<Mail server>>

package "Spring Boot Application" {
    [APIController] <<Spring REST controllers>>
    [AdminController] <<Spring REST controllers>>

    [AdminService] <<Spring service>>
    [DataStoreService] <<Spring service>>

    [Repository] <<Spring repository>>

User --> AdminController
ThirdPartyApp --> APIController

APIController --> DataStoreService
AdminController --> DataStoreService
AdminController --> AdminService

DataStoreService --> Repository
AdminService --> Mail

Repository --> PostgresDB


When we generate the diagram we see that each stereotype has it's own background color:

Written with PlantUML 8086.

Original blog post