Inbox display - address label/square color

Inbox display - address label/square color

Sorry if I'm not explaining this well, but I'm not even sure how to describe my question.

In the email Inbox display, between the subject line & the button to toggle read/unread status, there is a colored square box representing the sender's address. 

Funny that I never noticed it before today (maybe it was just added), but the colored boxes give a rather annoying, 'cartoonish' appearance to the Inbox.  Is there a way to get rid of the colored boxes and just show the sender's address  (or even just get rid of the color and have a white background in the box)?   Also, every time I refresh the Inbox window, the labels change color; this is quite annoying too.

I've gone through the Settings several times and find nothing relating to this, nor can I find the exact issue in the help pages.