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