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