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