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