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