One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,8)(6,7)(9,10)(11,15)(12,19)(13,16)(14,17)(18,23)(20,24)(21,22)(27,29)(31,33)(35,37)(39,40) involution — undirected(2,7)(3,8)(9,11,14,12)(10,15,17,19)(13,18,22,20)(16,23,21,24)(25,26,30,34)(27,31,29,33)(28,36,38,32)(35,40,37,39)(1,3,6,8)(2,4,7,5)(11,12)(15,19)(18,20)(23,24)(25,27,30,29)(26,31,34,33)(28,35,38,37)(32,39,36,40)(1,4,6,5)(2,3,7,8)(9,12,14,11)(10,15,17,19)(13,20,22,18)(16,23,21,24)(1,2)(3,4)(5,8)(6,7)(9,10)(11,15)(12,19)(13,21)(14,17)(16,22)(18,24)(20,23)(25,28,30,38)(26,32,34,36)(27,35,29,37)(31,39,33,40)(1,5,6,4)(2,8,7,3)(9,13,14,22)(10,16,17,21)(11,18,12,20)(15,23,19,24)(25,29,30,27)(26,33,34,31)(28,37,38,35)(32,40,36,39)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.