Scudellari's poem treats two colors, gray and lavender, as if they were characters with a shared history. Their "story" comes from the time they spent together, and the poem fills that time with fragments of imagery: high arcs, arranged yellows, the "lines of ocean scold," and a thin sliver of something passing by. It reads like a sky or seascape at dusk, though the poem never says so outright, so that is an inference from the imagery.
The speaker seems quietly admiring rather than dramatic. The last two lines carry the main idea: the colors tell their story only to "no one unwilling to hold its shine." In other words, it is meant for anyone patient enough to look closely and take in its glimmer. The mood is hushed, soft, and a little mysterious. The poem doesn't explain itself much, and that fits. Like a fading light, it asks you to notice rather than to analyze, and it rewards that attention.