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