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