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