Can a woman possessing 1 mutated allele show attenuated color-vision deficiency?
Short answer
Skewed X-inactivation may lead to phenotypic manifestation of X-linked color blindness.

Background
What an interesting question!

In a study by Jorgensen et al. (1992) two female identical twins that were heterozygotes for X-linked deuteranomaly were investigated. Phenotypically, deuteranomaly refers to anomalous trichromacy, i.e., reduced perception of a color. Note that deuteranopes are totally color blind. Deuteronomaly in the twins was associated with a defective gene derived from their father. Interestingly, while monozygotic twins are genetically identical, one of the twins was phenotypically deuteranomalous, while the other had normal color vision.

Analysis of skin cells of the color vision-defective twin revealed that almost all skin cells had the paternal abnormal X chromosome active, explaining her color-vision defect. In contrast, skin cells from her sister with normal color vision had predominantly the maternal X chromosome active. Hence, deuteranomaly in one of the twins could be explained by an extremely skewed X inactivation. 

As pointed out by @mdperry, extreme skewed X-inactivation is rare, and most heterzygous females for color blindness (carriers) are indeed asymptomatic (Jordan &amp; Mollon, 1993). Regarding your second question, all gene mutations leading to color blindness are recessive (NIH). 

References
- Jordan &amp; Mollon, Vis Res (1993); 33(1): 1495-1508
- Jorgensen et al. Am J Hum Genet (1992); 51: 291-8