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