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