One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,6)(5,8)(10,15)(11,18)(12,14)(16,23)(19,20)(22,24)(25,26)(27,30)(28,31)(29,37)(32,36)(33,38)(34,40)(35,39) involution — undirected(1,3,4,8)(2,5,6,7)(9,10,13,15)(11,16,20,22)(12,21,14,17)(18,24,19,23)(25,27)(26,30)(28,35)(29,33)(31,39)(32,40)(34,36)(37,38)(9,11,12,19,13,20,14,18)(10,16,21,23,15,22,17,24)(26,31)(27,33,35,34)(30,38,39,40)(32,37)(2,6)(5,7)(9,12,13,14)(10,17,15,21)(11,19,20,18)(16,24,22,23)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.