Do you have a FTS showing the light and tank together? If you're seeing good mantle extension and new shell growth, then all is well. Typically, clams don't change color, but can shift to lighter and darker versions of their current colors based on light (spectrum & intensity). They don't brown out, but can bleach due to lack of light or too high temp or stress.
As far as the color change from LFS to home, as stated earlier, lights and viewing angle play a major role in perception. To me, clams look like crap under blue light (and viewed thru the front glass), as it masks certain hues/pigments, but under daylight (6500k) their true colors really shine.
Most of us here want to help and we were confused by your initial post, as there were a couple red flags, which leads to follow up questions. Don't take it the wrong way, but if we don't know you, then there has to be a starting point for information that can fill in the blanks. I certainly don't want to offend or make fellow reefers feel bad, but after nearly four decades in the hobby, you see/hear a lot. When I worked in the hobby in the 90's, thru early 2000's, I often asked more questions of new customers, than answered. This allowed me to adjust my advice and truly help each customer to their needs. Some may have been dismissive, but for those that stuck around, they appreciated the advice and became long time customers in which I earned their respect.
Why am I typing all of this? Because, veteran reefers understand that it's not about your (or our) ego, it's about the care and well being of the animals we care for, nothing more. We are simply trying to help, but I understand that typed words can take us places we never thought and sometimes there's a loss in translation/context, which is truly misunderstood.
I'm not sure about the graph you posted, I'm a par and spectrum kinda guy, apologies.