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