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