Suppose, the data below shows the mean response time on a task for respondents among four different groups:
A B C D
1.2 2.3 4.5 6.7
In order to assess which one of the means are different from one another I do a multiple comparisons test (after an omnibus ANOVA test is cleared) and the multiple comparisons test tells me that the mean for group D is significantly different from the ones for groups A and B and no other pair of differences is significantly different.
What is the best way to present this information visually?