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)(27,32)(28,31)(29,37)(30,34)(33,39)(35,36)(38,40)(1,2)(3,7)(4,8)(5,6)(25,27)(26,32)(28,36)(29,34)(30,37)(31,35)(33,40)(38,39) involution — undirected(1,3,5,4)(2,7,6,8)(10,15)(11,17)(16,22)(18,23)(26,28)(27,35)(33,37)(34,38)(9,11)(10,12)(13,18)(14,17)(15,20)(16,19)(21,23)(22,24)(25,28,31,26)(27,36,35,32)(29,37,39,33)(30,38,40,34)(1,4,5,3)(2,8,6,7)(9,12)(10,11)(13,19)(14,20)(15,17)(16,18)(21,24)(22,23)(25,29)(26,33)(27,34)(28,37)(30,36)(31,39)(32,40)(35,38)(9,13,14,21)(10,16,15,22)(11,18,17,23)(12,19,20,24)(25,30)(26,34)(27,37)(28,38)(29,32)(31,40)(33,35)(36,39)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.