Essentially, gray means "would stay on daylight savings time," i.e., follow the time to their left in winter and to their right in summer. The colors mean "would stay on this time year-round." So if a state changes color, it means "drop DST and use summer time", and if it stays the same, it means "drop DST and use winter time."
The states that would stay on winter time are ID, AZ, CO, NM, ND, KS, OK, HI, AK, IL, MI, OH, NY, PA. The states that would stay on summer time are WA, OR, CA, MT, WY, UT, MN, IA, MO, AR, TN, MS, AL, FL, SC, NC, WV, DE, CT, RI, VT, NH, MA, ME, DC. Some are undecided as what to do (i.e., GA, TX and VA), while IN proposes to move to the Central Time winter time rather than stay in either Eastern summer or winter time.