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