While I updated that mockup... (added the table view switcher and the "add widget" icon) I came up with a new idea for your 'preset color triangles' :
Seems neater than the triangles, more streamlined and minimal, and you can make them do this when you mouseover them:
Fun fact:
The background color for the actions column in my mockups is derived from the iPhone 8 Gold color! The darker shades are more saturated versions of it.