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